CMC Triggers AR 15 Upper Receiver Parts Kit Dust Cover Forward Assist Black CMC AR15 UPK UPC 810169562475
Product Description
The CMC Triggers® AR-15 Upper Receiver Parts Kit (SKU: CMC-AR15-UPK / UPC: 810169562475) is a complete, duty-ready hardware solution engineered to finish stripped AR-15/M4 upper receivers. Manufactured to precise military standards, this kit provides every critical component required to establish environmental sealing and positive manual bolt closure in one consolidated, armorer-grade package.
Every individual component is built for durability under hard field use. The forward assist plunger and pawl are precision-machined from 4140 chrome-moly steel to resist repeated impact deformation against bolt carrier serrations. The ejection port cover rod is machined from high-tensile stainless steel with a resilient black nitride surface treatment, while the dust cover door and small hardware feature a non-reflective manganese phosphate finish for enhanced oil retention and corrosion protection in abrasive tactical environments.
Eliminating the hassle of tracking down mismatched, loose-tolerance small components, this assembly includes the forward assist plunger, spring, and roll pin, paired with the complete ejection port door, hinge pin rod, torsion spring, and C-clip retainer. Whether completing a high-tier duty build, assembling a custom competition upper, or replacing worn service parts, the CMC Triggers Upper Receiver Parts Kit delivers exact lockup and dependable mechanical operation.
*Armorer Bench Notes & Real-World Staging Guidance:*
Fitment Matrix: Fits standard Mil-Spec forged and billet AR-15, M4, and M16 upper receivers. CRITICAL: NOT compatible with large-frame AR-10, DPMS LR-308, or SR-25 receivers due to longer ejection port dimensions and different hinge pin placement. Ensure forward assist roll pin is driven with a dedicated roll pin punch to prevent mushrooming or receiver gouging.
- Ensure the workspace is organized, parts laid out, and the host stripped upper receiver is clean, deburred, and securely clamped in a dedicated upper receiver vise block.
- Install the ejection port cover by sliding the stainless hinge pin rod partially through the rear receiver lug, positioning the torsion spring with the long leg tensioned against the door, and advancing the rod until secured with the C-clip.
- Test the dust cover latching detent against the upper receiver pocket, verifying positive retention and immediate drop-down disengagement when pushed from the inside.
- Insert the forward assist pawl, spring, and plunger into the upper receiver housing with the pawl oriented toward the receiver bore centerline.
- Compress the forward assist plunger slightly against spring tension, align the roll pin passage, and drive the retaining roll pin flush into the receiver using a 3/32" roll pin punch before completing a BCG manual assist function check.
Key Features
- Complete Upper Small-Parts Assembly: Combines full forward assist and ejection port cover hardware in a single factory-matched kit.
- 4140 Chrome-Moly Forward Assist: Hardened steel pawl and plunger resist mechanical peening under heavy tactical usage.
- Nitrided Stainless Hinge Pin: Delivers smooth pivot action and total corrosion resistance against sweat, rain, and carbon fouling.
- Heavy-Duty Torsion Spring: Ensures instant, positive dust cover drop-down clearance during bolt carrier cycling.
- Mil-Spec Dimension Standards: Guarantees direct drop-in fitment across all standard forged and billet AR-15 upper receivers.
Product Specifications
- Brand: CMC Triggers®
- Model/Series: AR-15 Upper Receiver Parts Kit
- MPN / SKU: CMC-AR15-UPK / CMCAR15UPK
- UPC: 810169562475
- Forward Assist Metallurgy: 4140 Chrome-Moly Steel
- Hinge Pin Metallurgy: Stainless Steel (Black Nitride Treated)
- Dust Cover Material: Heavy-Gauge Ordnance Steel (Manganese Phosphate Finish)
- Finish: Matte Black / QPQ Nitride & Phosphate
- Platform Compatibility: Standard AR-15 / M4 / M16 Upper Receivers
- Country of Origin: USA
